The present invention relates to a rotary cultivator, and more particularly to a rotary cultivating apparatus of the laterally shiftable type comprising a tiller unit which is shiftable from tandem position to offset position and vice versa relative to a vehicle to which the apparatus is attached.
When a rotary cultivating apparatus is attached to a tractor or like vehicle for cultivation, the apparatus is usually positioned tandem relative to the vehicle as aligned therewith.
For cultivating a wet paddy field, for example, strakes, supplementary wheels or like running assisting means are attached to the vehicle, so that the cultivating apparatus, if connected tandem to the vehicle, is unable to fully cultivate the soil close to a boundary or ridge due to the presence of the assisting means. Further even when such assisting means are not used, the apparatus in a tandem arrangement sometimes fails to cultivate fully close to ridges.
Accordingly various rotary cultivating apparatus have been provided which comprise a rotary tiller unit laterally shiftable to an offset position relative to the tractor to which the apparatus is attached when cultivating the soil close to a boundary or bordering ridge. Such apparatus are very convenient because the soil can be cultivated completely close to the ridge and the area close the ridge can be subsequently treated easily. Rotary cultivating apparatus of this type include those of the slidable type which comprise a fixed frame having connecting portions for a tractor and an input gear case, a pair of opposite tubular support members attached to the fixed frame, a tiller frame having a rotary tiller unit and supported by the support members laterally shiftably, a transmission shaft inserted in one of the support members for transmitting power from a power input shaft to a tine shaft, and a shifting mechanism mounted on the other support member for laterally sliding the tiller frame relative to the fixed frame. The tiller frame (rotary tiller unit) is laterally slidable easily by operating the shifting mechanism after lifting the rotary cultivating apparatus, so that the apparatus has the advantage of being easier to handle for offsetting than those of the type wherein the connecting means of the apparatus for the tractor is replaced for offsetting. However, the conventional shifting mechanism, which comprises a hydraulic cylinder incorporated in the support member, requires a hydraulic piping system which includes control valves, etc., as well as seal means which must be prepared with accuracy. The apparatus therefore has the problem that it is very costly to manufacture.
The apparatus is further inconvenient to handle in that the means for changing the direction of lateral sliding movement of the tiller frame must be operated with a considerable force.